• Synthetic experiments in the benzopyrone series - Part XXX. A new synthesis of hydroxy xanthones including gentisein and gentisin

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    • Keywords


      Benzophenone; Xanthone; Benzoyl Chloride; Concentrate Sulphuric Acid; Dimethyl Sulphate

    • Abstract


      A new synthesis of hydroxy xanthones and their derivatives is described. It employs the Friedel and Craft’s reaction for the condensation of an ortho methoxy benzoyl chloride with a fully methylated polyhydric phenol. The resulting benzophenone has an ortho hydroxyl group which in a test case has been shown to belong to the phenol part. By subsequent treatment with aluminium chloride or hydriodic acid demethylation and xanthone ring closure are effected. As examples the synthesis of 1∶3-dihydroxy xanthone, 3∶4-dihydroxy xanthone and gentisein is given. The naturally occurring xanthone, gentisin is conveniently obtained by the partial methylation of gentisein or by the partial demethylation and ring closure of 2-hydroxy-4∶6∶2′∶5′-tetramethoxy benzophenone.

    • Author Affiliations


      G Venkat Rao1 T R Seshadri1

      1. Department of Chemistry, Delhi University, Delhi, India
    • Dates


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